Audiophile cappacitor replacement

Hi,

I have a question about the audiophile capacitor replacement. In normal production boards, signal coupling capacitor normally using polar electrolytic capacitors. In some higher grade models, bi-polar electrolytic capacitors will be introduced. Some people will upgrade it will audio grade capacitors such as oil caps, polypropylene caps. In my audio device, the coupling caps are 100uF polar electrolytic caps. I am looking for Jensen oil caps and it will be very expensive and the size is very big. Someone suggests me I can replace with 20uF oil caps instead of huge big one. If it is right, is there any rule of thumb to do the exchange calculation or any theory behind the idea. It seems the capacitor values will be 5 times lower than the original value and I am worry about the filter DC function. Thanks a lot for any input for the information.

Reply to
Eric
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Eric ha escrito:

This all seems rather unscientific to me, with more than a whiff of snake oil (dunno about capacitor oil!)

- since when can you reduce the capacitance to a fifth of the value of the original and expect good perfomance? What utter crap. You'd end up with a result as if the amp had aged 20 years and the caps had lost their capacitance. Use always the same value as the original: 100uF, with same or slightly greater voltage rating.

Unless there is a fault with the appliance, (often evidenced by hum, motor boating or excessive hiss on the output) I'd say don't mess about changing caps for the sake of it. You won't hear any perceptible difference. There are people out there making a living by spreading this nonsense about to the non-technical.

-B.

Reply to
b

Jensen copper foil / oiled paper caps as upgrade replacements, are usually more associated with the lower values that you tend to find as coupling caps in valve amplifiers. They are physically bigger than the bog standard polyesters that you would normally find fitted, and are very expensive. There is, however, a measurable improvement to be had by fitting them, but I would have to question if the cost was warranted.

Their electrolytic caps are, IIRC, all high voltage types for valve amp power supplies, so not appropriate for interstage coupling on semiconductor amps. As they are high voltage caps, their physical size will be correspondingly larger, so the only way to get the size back down, would be to reduce the value. I agree with the other poster, that this would be a bad move for the performance of the amp, and far from giving a performance improvement, would likely result in a detrimental effect.

There may be a measurable difference to be had, by replacing conventional interstage coupling electros with bipolar types, which are readily available, and no bigger than conventional types, but I doubt that you would be able to notice the difference in a real-world music playing situation. Again, I would agree with the other poster that if it ain't broke, don't try to fix it.If you want to know more about the subject, you could try the people over on uk.rec.audio. I know for sure that there are a couple of people there who have fitted Jensen caps to amps, and may be better able to advise you.

Arfa

Reply to
Arfa Daily

What measureable improvement ?

Have you measured it ?

Graham

Reply to
Eeyore

Hi Graham

I haven't personally measured any changes, but I have been assured by more than one genuine expert in the field, that an improvement in the dynamic response and overall flatness of the response curve of a high end - and we're talking 1200 quid monoblocks here - *is* both audible and measurable. I know what you're saying - or implying at least - and under normal circumstances, having been in this business for 35 years and having seen and looked into virtually every snake oil claim that there is out there, I too would be skeptical. However, knowing the credentials of the people who have made these claims, I have no reason to doubt them. I don't know whether you have ever been over on uk rec audio, but there are some furious debates that get going over claims about audible differences on cables, and it always comes down to measurable characteristics in the end, so that is why I am prepared to accept what has been said with regard to these caps, in this situation, by these people.

I genuinely believe that measurements with the appropriate equipment *have* been made, and a difference *has* been seen. At the end of the day, Jensen are a reputable company, and have been around for a very long time selling very high quality caps. Whilst I appreciate that this is not a recommendation for any claims per se, by the same token, in my experience, snake oil sellers tend not to last too long, before their claims are discredited ...

Be assured that unless I was pretty confident of what I was saying, I wouldn't actually say it on here, and potentially mislead someone that may be of lesser ability or experience than me. However, all of this has no relevance to the OP's original question, which I answered with what I believe to be an honest opinion, which is that attempting to replace electrolytic interstage coupling caps, with bipolars, will not result in any audible improvement to his equipment.

Arfa

Reply to
Arfa Daily

Well 5 of them will work. Some people replace passive speaker crossover components, but you have to watch ESR which can change requirments. I have seen certain types of electrolytics dry up and cause severe frequency response errors in coupling caps.

greg

Reply to
GregS

In general, replacing coupling caps with smaller values would create high-pass filters, so you will have less bass. Are you sure they really are 100u?

--
Met vriendelijke groet,

Maarten Bakker.
Reply to
maarten

I find some of this hard to believe. I guess a little bit of knowledge really is dangerous.

If anyone around here other than me knows how to design a transistor amplifier stage, they know the cap is critical to some extent. You cannot make the input impedance really high, like you can with a tube (valve) amp.When dealing with bipolars, almost any stage needs an emitter resistor and maybe even some bootstrap. Based on the gain of the transistor you can raise the input impedance, perhaps even use a common collector stage in front.

The problem is for a low distortion audio stage you need to drive the base with a smoothly changing current, not a solid voltage.

I have experimented too, I have made amps distort in a certain way, so I could see it on a scope as well as hear it, so I am not a babe in the woods here.

Now I say this, you make the input impedance and gain of the stage what you want, then select a coupling capacitor that will pass effectively down to like 10Hz. But when driving a tube (valve) or FET it doesn't matter as much. On high input impedance devices of course you need a resistor, in the case of a tube, from grid to ground as well as a cathode resistor to provide negative bias. In the case of FETs, well some of them are enhancement mode and don't need a source (cathode) resistor. Still if you intend to couple capacitively, there must be a resistor across it.

When the input impedance is really high, it makes sense not to shunt it out with a low value resistor. All you need is enough mhos to keep the leakage and a few other things out of the picture. The higher the value resistor, the lower value capacitance needed. Reactance + Ohm's law, simple.

On that note I will add, keeping the input impedance high is good for good sound. No capacitor is perfect. The thing is, what is imperfect about capacitors ? ESR and ESL. For the uninformed these are effective series resistance and inductance. (or just not up on all the three letter acronyms)

The impedance of a capacitor is the vector sum of it's actual reactance (admittance) and ESR and for higher frequencies the ESL must be brought into the equation. ESL can usually be ignored for audio frequencies, except maybe in high power crossover capacitors (in speakers, I mean passive crossovers)

No matter what the quality of the coupling cap, the higher the input impedance that it is couplinjg to, the better the quality. This is because the ESR and ESL become very minimal when a capacitor is feeding a high impedance.

Also, I totally disagree with switching to bipolar caps in any equipment, unless you have speakers so cheap that....nevermind that. To explain:

Capacitors have several variables. Size, capacity, voltage rating, ESR/ESL, longevity and cost. You shouldn't go lower in capacity and you can't go lower in voltage. If you get smaller caps they are likely to not have as low ESR and ESL ratings as the originals. If you get bipolars they will be bigger or have higher ESR and ESL at any given rating. That is unless they are made for current and if that is so they will either be bigger physically, or very expensive.

If the OP can supply me with a schematic of the unit, I might be able to come up with some good modifications. Wouldn't be the first time. Pioneer and Realistic both made mistakes in the FM stereo decoder, that was one I couldn't handle. The problem was inside the chip. All I could do is throw in a couple resistors to reduce the distortion but that resulted in a subdued high frequency response. See that's the other thing, in transistors, you never put a capacitor across an analog output unless it is ballasted, that is has a resistor in series with it.

Really the problem with these recievers was partly over modulation by the FM stations, but this IM and THC was coming from the earlier generations of PLL stereo demod chips. Although the signal wasn't really over modulated, it was more than the engineers expected. The result was that it sounded great on classical and some other types of music, but on hard rock it was almost intolerable. Especially on material that was REALLY in stereo, I mean had alot of seperation.

If anyone really wants to improve sound quality, let's face it, as long as the amp has less than 1% THD and IM, get away from it. No speaker is that good. Wonder why there is no THD or IM ratings on speakers ? You would shreik.

My speakers are actually among the very very few rated for THD. The rating is 0.7% at 1 watt 1Khz sine wave. And that is a fantastic rating for a speaker. At 10 watts it is probably up there close to double digit, but that is ALL speakers. They used to say that what comes out of a speaker is only as good as what goes into it, and that is absolutely true. But setting sights on the real problems is better than wasting a shitload of money on things that will not solve the problem.

I paid $400 for these BAs, they were ten years old and I paid MSRP for them, why ? Because I heard them. They rival Dahlquists and Cantons, other really good speakers of the days of yore. Big names do not even approach the sound quality of certain speakers. Pioneer, Bose, even Technics alothough their electronics used to be pretty good. Macintosh. Macintosh for _____ sakes !, not even close. Macintosh may have made some of the finest electronics in the world for audio, but they did not really excel in speakers IMO.

The only Mac I ever had was a Stereotech 1200, their first reciever. Little known, but I have it still even though it fried out. I had some Mac copies of their monoblock tube amps, but that is not the same. Later they came out with the Mac 4100, their first "official" reciever. Was nice too, cost alot too. But the brochure had the lid off, and you could see ALOT of similarity to the Stereotech 1200. ALOT. I mean it used the very same power amps, with darlington outputs in the SJ series from Motorola. Nice smooth gain curve on those SJ series outputs, very smooth for a darlington.

Anyway, I say this to all, if you want better sound, 90% of the time you need to look at speakers and speaker placement. Amps are pretty much how they are if designed properly. If they're any good at all you won't hear a difference. Of course they can put better tone controls on one and make it sound better in a certain environment. But the speaker makes the most difference.

JURB

Reply to
ZZactly

The term, "audiophile capacitor" is a red flag.

Reply to
Homer J Simpson

What's a genuine expert ?

And I were to tell you that they are complete knobs ?

Yes, they're quite barking mad and one of the guys who makes some of the most extravagant claims has utter rubbish for his 'system'.

By whom ?

Not in the audio business !

Biploars will make it worse actually.

Have you ever measured any capacitors?

I have.

Graham

Reply to
Eeyore

That'll be because they were poorly specified originally.

Graham

Reply to
Eeyore

For an output coupling cap it's very likely.

That's what I use myself for output coupling and it's pretty much standard in pro-audio.

There's a reason for it that's nothing to do with -3dB points btw.

Graham

Reply to
Eeyore

Dictionary opinion :- ex·pert /n., v. '?ksp?rt; adj. '?ksp?rt, ?k'sp?rt/ Pronunciation Key - Show Spelled Pronunciation[n., v. ek-spurt; adj. ek-spurt, ik-spurt] Pronunciation Key - Show IPA Pronunciation

-noun 1. a person who has special skill or knowledge in some particular field; specialist; authority: a language expert.

My opinion :- Someone who has successfully made a subject his life's work, and whose pronouncements are accepted as valued by more people who have an understanding of a subject, than rejected - hence my qualification of "genuine" rather than the unsubstantiated opinions that are put forward by someone who only *claims* themselves to be an expert.

Then I would have to tell you that that is a very jaded view, just your opinion, and not really sustainable. And to be honest, not the sort of input that I've come to expect from you, whose views I normally respect.

*Some* are quite barking, I would agree, but that does no preclude the fact that there are one or two on there who are respected figures in the field, and whose opinions I would consider to have more value than my 'broader understanding' ones, which are based on many years of repairing the stuff, rather than designing, modifying and speccing it ...

Errr ... By the people doing the measuring ??

Yes, in *all* businesses.

So I have to ask, and this is a genuine question, as you clearly believe that you, unlike the people on uk rec audio, are an expert, in what way will they make it worse, and why ? And if it is demonstrably the case, why do the likes of Musical Fidelity use them as interstage couplers as a matter of course in their high end preamps, and why do they get used as the C element in better quality crossovers ?

Of course I have measured capacitors, but for the characteristics that are important for repair purposes, not esoteric values that have an impact on design of the surrounding circuitry. I follow a rule that has served me well in the repair business for 35 years, and that is always replace like for like, and wherever possible, use either a manufacturer supplied component, or one from the same stable, so I do not normally need to start mesuring odd characteristics for speccing replacements for faulty components.

I hear what you are saying on all this, but really Graham, you are beginning to sound like one of those from that other group, who is barking. In the end, I gave the OP for this thread, what I believed was an honest and valued opinion. Clearly, you think otherwise, and if you are making claim to being whatever counts for you as a *true* expert in the field, then I bow to your superior knowledge. We have had some good exchanges and have given what I consider to be good joint advice in the past, and I have no desire to fall out with you over this one, so that's all am going to say on the matter, and unless anything else appears in this thread that requires me personally to answer, then I now bow out of it ...

Arfa

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Reply to
Arfa Daily

What the Hell is a "esoteric value"? How does one measure "esoteric values"? Is there a "esoteric value" meter?

I am sure you own a good cap checker. If you do, it probably measures capacity, leakage, ESR, and breakdown.

If your trying to quantify some other test, then somebody needs to explain it or it is snake oil. Now, if someone is sweeping a cap from 20 to 50K with a audio signal and measuring variations in ESR or such and can show a "VALID" difference, then that is a quantifiable test. If that is what they are doing, then the test needs to be stated with test conditions and type of equipment used.

There are cheaper electrolytics these days as i am sure you know. Especially the little surface mount guys that have the 1/2 life of a mouse being chased by a hawk. ANd then the infamous "we stole the wrong cap formula" fiasco of a while back. So i am not totally against the "defective cap" theory.

And how do you quantify the final result? Just saying it sounds "warmer"? Unless its something you can measure on test gear, how do you prove it? Only a qualified golden ear may apply? And how much of a difference is it? Is the response smoother? less noise? lower THD? Less phase variation?

You want to find some real HI-fi experts go down to aus.hi-fi. ;)

Like politics, audio has its "spin doctors" that can convince gullible people of anything. I imagine some people are still putting green magic marker on there CD's and swearing they sound better.

Unfortunately, audio is going in the wrong direction. It used to be the industry fought for another .1% drop in THD. Now we have lossy formats such as MP3 whose sonic purity is questionable at best. And cheap home theater receivers where 1 or 2% THD is the norm these days. I call it the "dumbing down" of our ears. And don't forget the disposable gear that's so cheap its not fixable. Its the beginning of the end of the consumer electronics repair industry as we know it.

Bob

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Reply to
Bob Urz

Oh dear ! Clearly, English is your native language, but it would seem that there are some words that you just haven't come across ... Do they not have dictionaries wherever you are ? I actually agree with most of what you have said, and I never implied that I believed in golden ears, or anything else in the same vein. All I said, that seems to have created the rather vitriolic response from Graham, was that I genuinely believed that there were measurable differences in the performance of "audio grade" caps over bog standard types, and that there were people out there who had made those tests. The reference to "esoteric values" is a tongue in cheek allusion to the 'snake oil experts' who will present complex-sounding measurements that are actually bollocks. For your further education ...

es·o·ter·ic /??s?'t?r?k/ Pronunciation Key - Show Spelled Pronunciation[es-uh-ter-ik] Pronunciation Key - Show IPA Pronunciation

-adjective 1. understood by or meant for only the select few who have special knowledge or interest; recondite: poetry full of esoteric allusions. 2. belonging to the select few. 3. private; secret; confidential. 4. (of a philosophical doctrine or the like) intended to be revealed only to the initiates of a group: the esoteric doctrines of Pythagoras.

--------------------------------------------------------------------------------

[Origin: 1645-55; < Gk esoterikós inner, equiv. to ester(os) inner
  • -ikos -ic]

-Related forms es·o·ter·i·cal·ly, adverb

-Synonyms 1. abstruse, arcane, cryptic, enigmatic. Dictionary.com Unabridged (v 1.1) Based on the Random House Unabridged Dictionary, © Random House, Inc.

2006. American Heritage Dictionary - Cite This Source es·o·ter·ic (es'?-ter'ik) Pronunciation Key adj. 1.. 1.. Intended for or understood by only a particular group: an esoteric cult. See Synonyms at mysterious. 2.. Of or relating to that which is known by a restricted number of people. 3.. Confined to a small group: esoteric interests. 4.. Not publicly disclosed; confidential. 2.. 1.. Confined to a small group: esoteric interests. 2.. Not publicly disclosed; confidential.

[Greek esoterikos, from esotero, comparative of eso, within; see en in Indo-European roots.]

es'o·ter'i·cal·ly adv.

(Download Now or Buy the Book) The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2000 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved. WordNet - Cite This Source esoteric

adjective confined to and understandable by only an enlightened inner circle; "a compilation of esoteric philosophical theories" [ant: exoteric]

Arfa d;~}

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Reply to
Arfa Daily

Sure. It's called an E-Meter and your local Scientology Centre has them.

Reply to
Homer J Simpson

One parameter that might be considered esoteric, is delectric absorbtion. This will affect capacitance, but can be measured out. it can affect DC circuits, or ac circuits with a dc bias. Better caps have low DA. Electrolytics are really bad in this respect. DA also causes frequency dependant cap values.

greg

Reply to
GregS

Dam, that's got me jumping on the sofa! ;)

will affect

circuits with a dc

DA also causes

Now were cooking on gas. Define what can make a difference. Frequency dependent values. Now, you have to define a standard repeatable test to quantify the results. Other wise its smoke and mirrors again. Is there a Audio standard that i know about how to do this? not really. So pick a arbitrary test set up and call it fact? To do this, you would need to define frequency range. drive and load impedance. and what deviation from standard parameters constitute an audible difference. I suppose its not beyond the realm of possibility (if you define the above test and criteria) to select caps like how you match vacuum tubes for characteristics.

A few interesting links on the subject:

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Bob

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Reply to
BOB Urz

--------------------------------------------------------------------------------

Ok, you have a dictionary definition of esoteric. You have so called experts telling you what esoteric is. What are there qualifications? I don't recall seeing any engineering school classes on esoteric. What makes these guys so much smarter than everyone else? And why is so much of the stuff Voodoo science it seems? And VERY costly to boot?

Like i said before, test caps with a standard, quantifiable test of some sort. and put the charts with it to show in black and what what the differences are. And under what conditions, loads and voltage ratings. Anybody can tell or sell you anything. that does not make it true or better. There are still people selling magnets that go on automotive fuel lines that claim give you better mileage. After all these years! PT Barnum was right. ;)

I am not against better quality components of any nature. But i want to see the proof. Being in the service industry for years, i am all for the best bang for the buck. These days its a matter of survival in the service industry. In the quest for that, i have been on both the good and bad end of component sourcing. Sometimes you just need to find out for yourself.

Bob

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Reply to
BOB Urz

Eric: When you get done with this expensive waste of money.... please contact me so I can sell you very expensive oxygen free, biradially wound copper speaker wires and interconnect cables with gold connectors...about $10 per foot...... and while you are at it you should consider a $1500 or more, power line conditioner so that your equipment gets cleaned up power so it can produce much "improved" sound. Daniel Sofie Electronics Supply & Repair

- - - - - - - - -

electrolytic

grade

it

lower

Thanks

Reply to
Sofie

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